my 1994 ford f-150 has no pep and burns allot of gas, is this a sensor issue? if so which one?


Asked by May 31, 2015 at 09:21 PM about the 1994 Ford F-150 XLT LB

Question type: Maintenance & Repair

the truck doesn't take off no matter how much you hit the gas, once you get going it cruises good. It also seems to burn too much gas. its a 94 F150 xlt with a rebuilt motor and new tranny. 2 wheel drive.

8 Answers


Hello, Much been going on with that one... Key: new tranny/motor Does the transmission actually shift, or does it feel like you are taking off and it just gains speed? The E40D is a bear for the average tranny guy; so, start with the selector in 1 and shift my hand, does it make a difference?? All aspects of that motor are ECM controlled, so an overfueling/underfueling condition means much. Any sensor that was getting a bum reading would change many aspects of normal running. Does the check engine light work? Tell me more... Thanks, AskTrannyMan

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No check engine light (it does work), I was having issues with the overdrive but the tranny place corrected that and overdrive does work. It does shift but sometimes I feel it takes longer to shift gears. I will try manual shifting the gears tomorrow morning to see if that does anything. I purchased an 0-2 sensor on ebay and will try to change that when it arrives. The truck has 135,000 miles on it. The engine was rebuilt at 99,000 miles. The tranny was rebuilt at about 120,000 miles.


Hello, Very good, your time on the 02... Can you tell me when you noticed the most degraded performance...after the engine or tranny job? Thanks, AskTrannyMan

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Best Answer

Sounds a lot like what my daughter's 99 with a 4.0 pushrod engine was doing. Turned out to be a tuneup issue. Check the resistance on your spark plug wires before replacing. Use Motorcraft plugs and wires if necessary.


before the engine was rebuilt it was sluggish and i had no compression in one cylinder. I was told it was a cracked valve. So I decided to rebuild the motor. Now its not as bad as it was but still not right for a 5.0 motor. no balls at all. sometimes it feels like its struggling to get up to speed but once i'm going over 50 mph it seems better. Also when I first start it cold it wants to die or stall for about 5 seconds then rev's right back up. very odd.


I put a super duty clutch fan in it and it sounds like its pushing heavy air like a wind tunnel. TrannyMan's got me thinking....I changed the radiator and added in the heavy clutch fan, could that be doing anything negative? Also the heat in the truck never gets hot in the winter and someone told me it was air locked in the radiator but flushed it through a few times. I'm starting to think the superduty clutch for the fan might be a part of my issues?.


Hello Al, Just gettin' in for the day... Well now you have told me much... A heavy duty fan clutch is actually a real big NO-NO. I can't tell you the HP that one takes... We went thru that in the early 80's on GM's... Napa was my favorite parts place...always pushed the heavy clutch. I had to go out of my way to get the OEM SYTLE. Now, the rest tells me more... You are probably not even getting to operating temp, but that is not the fan clutch. Make sure the thermostat is correct...I mean no 180°...the correct one 195° or 205°. Drill a 3/64th hole in the thermostat to allow it to bleed easier. Sure fix for Many Engines. I was leaning toward the open loop, low ignition timing thing...everything you describe sounds like an engine that is running way retarded, and too lean. With that said, since you burnt a valve or cracked it....from too LEAN, because a lean mixture burns MUCH hotter that either the correct (Stoichmetric) or rich mixture, this leads me to believe that your knock sensor is bad, or the wires are shorted, grounded, open. A bad KNOCK sensor on the side of the block will cause all kinds of retarded ignition timing, and funky mixture of all the BIG 3 (GM

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cont'd... So, find a good shop, hire one of their best off the clock for a night, and let him hook a scanner to this engine, and check all the items I mentioned,...Correct Temp,...Correct timing advance, with retard when you hit the knock sensor with an extension, and Mixture. Keep us informed, and Good Luck AskTrannyMan

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